A microspectroscope is an apparatus that includes an observation optical system for microscopically observing a sample surface and an analyzing system for performing a spectroscopic analysis on a part or the whole of an observed area. For example, a microscopic infrared spectroscopic analyzer that performs an analysis with infrared light includes, as the analyzing system, an illumination optical system for emitting infrared light, an aperture for casting the infrared light only on a specific small area of a sample surface, and an infrared detector for detecting light reflected by or transmitted through the sample and passed through the aperture. Hereinafter, the microscopic infrared spectroscopic analyzer is merely referred to as “infrared microscope”. The infrared microscope obtains the observation image of visible light on the sample surface by means of the observation optical system, and the position, size, and orientation (angle) of the aperture are set based on the observation image of visible light.
In the infrared microscope, normally a user visually examines the observation image of visible light, and sets the position, size and orientation of the aperture one by one by means of a pointing device such as a mouse. However, when the spectroscopic analysis must be done on a large amount of samples, such as analysis of impurities in the course of product quality management, it is labor and time consuming for a user to manually set the position etc. of the aperture. Accordingly, there has been provided an infrared microscope in which a characteristic image region is extracted from an observation image, and the position etc. of the aperture are automatically set for the region.
For example, Patent Literature 1 discloses an infrared microscope in which an image processing such as edge extraction or binarization is performed based on the hue or illuminance of the observation image of a sample, so as to extract the characteristic image region. Another kind of infrared microscope is known in which when a user designates an appropriate position in the observation image with a pointing device or the like, a region having an illuminance value, for example, in a predetermined range centering on the illuminance value of the designated position is extracted as a characteristic image region.